Re: Radiator overflow tank?
 

Yeah, I figured yours was also rotted - BUT - I do need one with a complete label on it to have the label reproduced - all three of mine are missing some section of the label and it can't be scanned to re-create a new one. Is the label complete on the one you have by chance? if so can you post a pic?

Re: Radiator overflow tank?
 

Not sure how to locate the part number for these Jon - I have a huge master parts catalog for GMC through the 60's so I'll see if I can find it. GMC took the time to change the label design for the overflow tanks used on factory AC trucks so I feel like there is a GMC part number in a master parts book but unless it was offered as a stand alone accessory option (which it obviously wasn't) it would not show in the accessory guides, and it would not show in any Chevrolet books unless used on them, and to my knowledge they were not added to any Chevy trucks after 1955. So this is probably a GMC-only item, and with exception of Petes' unusual example they were on all assembly-line installed AC trucks regardless of 305 vs 351. I have found them on both and have collected three tanks off factory AC GMC trucks so far so we can find a part number I feel like - need to see what the master parts book shows us

Re: Radiator overflow tank?
 

How do you know this Steve ? quote " they were on all assembly-line installed AC trucks "

Re: Radiator overflow tank?
 

I've personally owned or found 4-5 factory AC trucks (more than just about anyone in the country) and every single one had one of these tanks on it or had inner fender holes where one had been - so is it possible for any factory AC truck to have come off the assembly line without one? Possibly - but doubtful. Factory AC introduces more heat and strain on the engine, so that is why every factory AC truck also has a 4 flu radiator in it too vs the more usual 3 flu on V6 equipped trucks, so bigger radiator for greater cooling, and an overflow reservoir was added. Plenty of GMC trucks came with dealer-installed AC units and I have so far never seen one of those installations include a reservoir - only assembly-line installed units using the A6 compressor and riveted-in well nuts in the dash seem to have these.

Re: Radiator overflow tank?
 

My question was more at how you know they were on the truck on the assembly line.

Re: Radiator overflow tank?
 

nobody can prove something was on a truck off the assembly line unless they have the ppwk showing it, or they themselves were working on the line and happened to snap a picture - all we can do is observe untouched original trucks for how they appear to have come when all the hardware and related placement etc mirrors that of other known untouched original examples. I have no oubts of any kind that these overflow tanks were installed at the assembly line level and no one can prove they weren't just the same as maybe I can't prove they were.
After seeing several examples of factory AC equipped trucks all having these tanks, it only makes sense that they were obviously part of the standard equipment commonly installed on AC equipped trucks - that's my take on them until someone proves they are dealer installed or something

Re: Radiator overflow tank?
 

The "overflow condenser" shown by Groby and others was definitely an accessory in the 50's and earlier. It was used on vehicles without A/C. It was used in vehicles without special radiators. Just guys adding a neat aftermarket gizmo they didn't need.
If they are "Factory", GMC would have mounted them in exactly the same place with exactly the same bracketry, hoses and hardware; and be the same unit with GMC logo. The fact that they are on A/C truck with larger radiators just means that GMC could have used larger radiators with A/C. Does not mean that the "overflow condenser" was installed at factory. The overflow condenser does not keep the radiator from over heating due to more "heat and strain" anyway. If they used a bigger radiator so that it would handle the A/C "strain", it would handle it.
The examples I see so far on this post show that the units were not mounted the same. They look aftermarket/dealer units.
If the vendors thought it was used in 60-66 they would surely include those years for more sales.
Until it is found on a build sheet or in a GMC document for 60-66, it should not be labeled "Factory", that's my take on it. Just an opinion not hostility.

Re: Radiator overflow tank?
 

What "untouched originals" do we have to look at ? I haven't seen ANY nice original GMCs with AIR that were untouched. I spent a good part of my day looking through 1964 1965 1966 print dated GMC parts books and older books back to the mid 50s , no cans. The only radiator surge tanks I found were for BIG trucks. Zero applications for 1000 to 2500 series trucks and no listing at all to do with AIR. Without a picture of these parts matching these numbers I found, its impossible to say if they are the same ,but the books do not lie. If theres not a part number to application , theres no such "factory" part. The only theory that makes any sense is the can pictured of Steves was a service option made in the aftermarket or one of the BIG truck cans retrofitted to fix customer concerns. To say its factory without proof , or because you had a truck with one , or several , still does not mean it came off the assembly line this way. Every "original part" can be traced. So far , these cannot be.

Re: Radiator overflow tank?
 

The one I pulled off was from a 66 351E with no air conditioning. The setup was exactly the same as GMCNUT's right down to the mounting, I also found it's basically the same tank that was used in the 30's, 40's and 50's. I will check this weekend for any possible part numbers, the label on it is pretty faded out. I seriously doubt these were installed by a service station as they are a real GM Part, more research needs to be done to figure why there was no info listed anywhere.

Re: Radiator overflow tank?
 

Ken / Jon - the GMC factory installed radiator overflow tanks on AC trucks have a special bracket made to fit a very specific spot on the right inner fender behind the battery - in 100% of the cases I have observed including all THREE tanks I pulled and saved here, they were mounted in exactly the same spot. I know you guys don't like to believe the books are ever wrong but they are sometimes wrong I hate to tell you. Jon's 1964 Chevrolet Data book does not show a 327 V8 option for 64 1 ton C30 trucks, but somehow magically he now has one with that very motor and with assembly line installed AC no less - something else hundreds of book believers didn't think could happen. Jon's C30 has all the ppwk showing the 327 and shows assembly-line AC both being ordered for it - so look guys - we can beat a dead horse a thousand times over trivial stuff, but I am telling you from EXPERIENCE - these 65-66 GMC AC trucks have Radiator overflow tanks on them that have been there from day 1 regardless of what the books all say or what the books omitted. The only book any of you can count on is the Bible - other than that, they are often as flawed as those who wrote them.